Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $92.29   4.350%   $96.3046   $96.30   $96.30   $96.30  
  Purchase #2 $134.39   3.132%   $138.5991   $138.60   $138.60   $138.60  
  Purchase #3 $246.77   5.559%   $260.4879   $260.49   $260.50   $260.50  
  Purchase #4 $212.93   10.856%   $236.0457   $236.05   $236.05   $236.00  
  Purchase #5 $177.59   6.727%   $189.5365   $189.54   $189.55   $189.50  
  Purchase #6 $89.50   5.249%   $94.1979   $94.20   $94.20   $94.20  
  Purchase #7 $85.25   6.676%   $90.9413   $90.94   $90.95   $90.90  
  7 purchase totals = $1,038.72       $1,106.1130   $1,106.12   $1,106.15   $1,106.00